1. Technical Field of the Invention
The present invention relates to skincare products containing a first anhydrous composition comprising at least one compound of the avermectin family or a compound of the milbemycin family, and a second composition, as a combination product for the treatment of dermatological conditions/afflictions.
2. Description of Background and/or Related and/or Prior Art
The avermectin and milbemycin families constitute a group of macrocyclic lactones produced by the bacterium Streptomyces avermitilis (Reynolds JEF (Ed) (1993) Martindale. The extra pharmacopoeia, 29th Edition, Pharmaceutical Press, London). Avermectins include in particular ivermectin, invermectin, avermectin, abamectin, doramectin, eprinomectin, emamectin and selamectin. Milbemycins include in particular lepimectin, milbemectin, milbemycin oxime, moxidectin and nemadectin.
Ivermectin, a compound of the avermectin family, is the preferred compound according to the present invention. Ivermectin is a mixture of two compounds belonging to the avermectin class, 5-O-demethyl-22,23-dihydroavermectin A1a and 5-O-demethyl-22,23-dihydroavermectin A1b. They are also known under the name 22,23-dihydroavermectin B1a and 22,23-dihydroavermectin B1b. Ivermectin contains at least 80% of 22,23-dihydroavermectin B1a and less than 20% of 22,23-dihydroavermectin B1b.
In the mid-1980s, ivermectin was presented as a broad-spectrum anti-parasitic medicament for veterinary use (CAMPBELL, W. C., et al., (1983). Ivermectin: a potent new anti-parasitic agent. Science, 221, 823-828). It is effective against most common intestinal worms (except taenias), most mites, and a few lice. It has in particular a high affinity for glutamate-gated chloride channels present in the nerve and muscle cells of invertebrates. Its attachment to these channels promotes an increase in membrane permeability to chloride ions, causing hyperpolarization of the nerve or muscle cell. This results in a neuromuscular paralysis which can cause the death of some parasites. Ivermectin also interacts with other ligand-gated chloride channels such as those involving the neuromediator GABA (gamma-aminobutyric acid). Ivermectin is more particularly an antihelminthic. It has already been described in humans in the treatment of Onchocerca volvulus onchocerciasis, gastrointestinal strongyloidiasis (anguillulosis) (product Stromectol®), human sarcoptic scabies (Meinking T L et al., N. Engl. J. Med., 1995 Jul. 6; 333(1):26-30 The treatment of scabies with ivermectin) and in the treatment of diagnosed or suspected microfilaraemia in subjects suffering from lymphatic filariasis caused by Wuchereria bancrofti. 
In addition, international application WO 2004/093886 discloses the use of ivermectin for the manufacture of a topical pharmaceutical composition intended for human use. More particularly, this application discloses the use of topical pharmaceutical compositions intended for human use comprising ivermectin for the treatment of dermatological conditions such as rosacea, acne vulgaris, seborrhoeic dermatitis, perioral dermatitis, acneform rash, transient acantholytic dermatitis and acne miliaris necrotica.
However, the low compatibility of ivermectin with many excipients (N. O, Shaw, M. M. de Villiers and A. P. Lötter, Pharmazie, 54 (1999) 5, 372-376 Preformulation stability screening of ivermectin with non-ionic emulsion excipients), and its low solubility in water mean that pharmaceutical compositions containing ivermectin generally require either the addition of a large number of additives which make it possible to obtain stable compositions, which has the effect of increasing the risk of allergies, or to be formulated with anhydrous excipients. The anhydrous compositions encountered conventionally have the disadvantage of a greasy feel and therefore of an appearance that is not very cosmetic, which may be responsible for a decrease in patient compliance. In addition, by virtue of the low stability of ivermectin in water, the shelf life of aqueous compositions containing ivermectin is generally shorter than that of anhydrous compositions containing ivermectin.